C.) The environment is seldom affected by technological advances.
You can export best what you produce in great amount and Southeast Asia is know for producing great amounts of rice -so rice is the correct answer!
In fact, they would more likely import wheat and corn, as they probably don't produce enough even for their own needs.
They are called sedimentary rocks
Nuclear fusion generates the energy that is released by stars.
In the great majority of stars, it's the fusion of hydrogen nuclei
to form helium nuclei plus energy. In very old stars, the nuclei
of heavier elements are fused, forming even heavier ones.